Available electronic sensors measure a variety of values, such as, pH, color, temperature, or pressure, to name a few. For systems that require a string of electronic sensors over a long distance, e.g., twenty to thirty kilometers or longer, powering the electronic sensors becomes difficult. Conventionally, the powering of electronic sensors requires running electrical wire from a power source to each of the electronic sensors. However, electric wires spanning such long distances create too much interference and noise, thereby reducing the accuracy of the electronic sensors.
Optical fibers have become the communication medium of choice for long distance communication due to their excellent light transmission characteristics over long distances and the ability to fabricate such fibers in lengths of many kilometers. Further, the light being communicated can also power the sensors, thus obviating the need for lengthy amounts of electric wire. This is particularly important in the petroleum and gas industry, where strings of electronic sensors are used in wells to monitor down hole conditions. Powering electronic sensors electrically has been a problem in the petroleum and gas industry.
As a result, in the petroleum and gas industry, fiber optic sensors are used to obtain various down hole measurements, such as, pressure or temperature. A string of optical fibers within a fiber optic system is used to communicate information from wells being drilled, as well as from completed wells.
Conventionally, each sensor in a multi-sensor fiber optic system is calibrated to a particular communication channel. Thus, each sensor sends data back to a dedicated communication channel. Currently, calibration coefficients for each communication channel, which are necessary to ensure that data from a particular sensor is communicated to the proper channel, are manually entered. If a particular channel is defective or, for whatever reason, cannot be used to receive data, the calibration coefficients for the respective sensor have to be manually re-entered into another channel, increasing the possibility of human error.